Julia has greatly benefited from the Google Summer of Code. In the last 5 years, over 50 students have contributed to Julia and various Julia packages. Many of these students have become regular Julia contributors well beyond their summer projects. Take a look at the Ideas Page and contribute your ideas.
10 Julia projects were supported in GSoC 2016.
Various projects were proposed by the community in GSOC 2015. However, Julia did not make it to GSOC 2015. Julia organized its own Summer of Code this year thanks to a generous sponsorship for the same from Gordon and Betty Moore Foundation. The projects in Julia Summer of Code 2015 were.
Julia was accepted as part of GSOC 2014. Many of the contributors in GSOC 2014 were mentors for JSOC 2015.